The present invention relates to a power operated rotary knife that has an improved handle assembly.
Power operated rotary knives have been used in commercial meat processing operations to trim fat and connective tissue from meat, trim pieces of meat from bones, and to produce meat slices. Such knives are often constructed so that they are driven via a long flexible drive shaft. The knife operator wields the knife relatively freely at a meat cutting work station that is remote from the driving motor.
These power operated knives represented a major improvement over use of hand knives or knives having an integral drive motor. Knife operator fatigue was greatly reduced, enabling both increased productivity and greater knife operator comfort. Nevertheless knife operator fatigue was not eliminated. Some knives incorporated xe2x80x9ctake-withxe2x80x9d handles that were sized to fit the hands of knife operators using the knives. These handles could be removed from the knives and taken with the knife operator after using the knife. Take-with handles reduced fatigue because the knife operator could always use a knife with a handle that was properly sized. The handles were difficult to install in proper alignment with the knife blade.
Some previously known rotary knives were provided with steeling mechanisms. But these were not convenient to use because the knife operator had to significantly reposition the knife hand or use two hands to steel the blade.
When the blades of rotary knives must be replaced, the blade is removed from its housing on the knife. In many prior art knives, removing the blade was difficult and required the blade housing to be semi-detached from the knife in order for the blade to be removed and replaced. This required significant operator time and skill to achieve because the blade housing and associated parts had to be properly aligned for the knife to perform optimally. In other knives a special blade removal mechanism was incorporated in the knife. This increased the knife weight and added to the cost of the knives so equipped.
The drive connection between the flexible drive shaft and the blade rotating gearing was typically formed by a square cross section flex shaft end that plugged into a square opening in a drive gear. The blade drive was disconnected by pulling the flex shaft end out of the drive gear opening. The resultant engagement forces between the faces of the flex shaft end and gear opening had force components that were radially directed as well as normal to the radial components. The normal force components were effective to transmit torque and were of smaller magnitude than the respective engagement forces. Therefore, for a given amount of torque transmission, the frictional forces resisting disconnection were great because the frictional forces were proportional to the engagement force. This tended toward increased difficulty in disconnecting the blade drive.
The present invention provides a new and improved rotary knife comprising, an annular blade having a central axis, a blade supporting head assembly supporting the blade for rotation about the axis, a manually grippable handle assembly connected to the head assembly, and a flex shaft drive transmission for driving the blade about the axis.
An important feature of the invention resides in the handle assembly construction. The handle assembly comprises a core, a hand grip surrounding the core, and a connector unit that secures the hand grip to the core. The core has a first end region rigidly fixed with respect to the head assembly and a second end region spaced from the head assembly. The core defines a drive transmission guiding channel leading toward the blade. The hand grip has a first end region proximal the blade support assembly and a second end region proximal the second core end region. The connector detachably secures the hand grip in fixed relationship with the core. The connector engages the second end regions and is detachable for enabling hand grip removal and replacement.
The hand grip is provided with an alignment key element that coacts with one of a number of slots that are fixed with respect to the core and head assembly. The hand grip is manipulated to properly align it with the head assembly and the alignment key is moved into the appropriate slot before the connector secures the hand grip to the knife.
According to a preferred embodiment, the connector unit engage the core and clamps the hand grip into fixed relationship with the knife. The connector unit comprises a latching mechanism that detachably secures the drive shaft assembly to the handle assembly in a condition where the drive shaft assembly and the blade are disengaged.
According to another feature of the invention a steeling mechanism is provided that is easily accessible to the knife operator so that the operator can steel the blade without repositioning the knife hand and without the need to use two hands to accomplish the steeling procedure.
Still another feature of the invention provides for drive transmitting forces to be transmitted between blade driving gearing and a flex shaft assembly in directions that are normal the radial lines through the rotation axis. These driving forces do not have radial components and accordingly, for a given torque transmission, frictional forces resisting disconnection of the drive are minimized.